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Everything posted by Ajohn

  1. Gumtree and PreLoved are worth a look as well. There are always some on there. Also any for sale newspapers. There are good lathes on Ebay too, that's where my Boxford came from. Sometimes VAT is involved as dealers sell any where they can. Approached directly there is a possibility this might be avoided by smaller ones. Some people have asked around on industrial estates to see if any one has machines they might sell. There are also a number of local model engineer / train clubs around, easy to find with google. Not sure about reviews in magazines. Like the web sites that specialise in certain models all seems to be wonderful. Searching the web for a few hours on particular models can be more useful. Preparing a Chinese lathe. This was produced by ArcEuro for one of the lathes that they sell http://www.arceurotrade.co.uk/projects/prepguides/C3%20Mini-Lathe%20Preparation%20Guide.pdf It includes changing the bearings which needn't be done but the new ones are likely to be better - hardened taper rollers. It's mostly concerned with minor problems. Some one on another forum bought one of these and noticed that the tailstock and head stock centre height didn't match. Went at it like a bull in a china shop lapping material of the base of the tailstock and later found that there was another problem as well. I did suggest that he did some simple turning tests first but ............ If anyone attempts something like this it really is best to study the machine carefully for all problems before trying to fix the most noticeable one. In this case it looks like the headstock bearings were a little loose. Might influence what he had noticed or might not but best to find out first and also look for all errors in the machine before doing anything at all. Removing paint and cleaning up edges etc is just something that should be looked at and fixed if it needs it. It just pays to be very careful about doing anything else. John -
  2. Best advice really is to wait and choose carefully. One small Myford comes up from time to time that might suit. The ML10 and Speed 10. There is a catch with those though. This the early ML10 http://www.ebay.co.uk/itm/myford-ml10-lathe-/121702335020?pt=LH_DefaultDomain_3&hash=item1c5606422c The thing to note is the bolt heads on the headstock bearing caps and the oilers. The front one is right behind the chuck. You will read on lathes co uk that this steel running on cast iron is wonderful. It isn't as nothing can be done with them once they are worn and they do wear. The later ML10 and Speed 10 use taper roller bearings and there are no bolts just an oiling nipple. The difference can be seen clearly in this photo. The Speed 10, later ML10 and Diamond 10 are exactly the same. The ML10 in this form just has a lower top speed. http://www.lathes.co.uk/myfordml10/img4.jpg I don't know of any other half decent recent UK made small screw cutting lathes. I've never seen any steadies for them so if some did come up they would probably fetch high prices. Buying the change wheels for screw cutting individually would work out rather expensive. They are 13in between centres, have a 3 1/2in centre height and are about 3ft long. They sometimes come with no stand and the motor unit separate. Myford did some castings to mount them on but 1/2 in aluminium plate or a decent thickness of wood could be used or just bolted to decent bench. The problem with 7's is that they are cheap budget lathes really compared with what might be called real lathes off Colchester and outfits like that. This is why they can turn up rather worn. Personally I feel a used Boxford is a much better bet but most of them come with a stand with the motor built into it. There is a very old model C on ebay, bench mountable but sorting out what would be needed to go with it, things such as change wheels even for just power feed would work out expensive. The power feed on the newer ones is different. A lathe with a gearbox will have what wheels it needs for imperial threads in it otherwise they are best bought with a set. The feed on these is geared down from a slot in the leadscrew. The very new ones that can still be bought new work out at about 15k. These crop up used at all sorts of prices. They could be taken off the stand and bench mounted but they are pretty heavy. The warco that would interest me is this one http://www.warco.co.uk/metal-lathes-metalworking-lathe-machine/303011-warco-gh550-gear-head-metal-lathe.html but I would want to be sure it sounds like a gear head lathe with hardened and ground gears should. It's so heavy that I doubt if the kitchen unit my Boxford sits on could take it. It's a lot of lathe for the money - maybe too much. There is also the 240B. Why belt drive? More torque than will be available on the variable speed ones at lower speeds for drilling but a min speed of 125rpm is a bit fast for some screw cutting. The ML10 is back geared. Boxford too and many rather old lathes = much lower speeds for screw cutting. The person who bought the ML7 will probably finish of their work with a file and emery cloth. That is another option. The same is likely to be true with many of the old lathes that come up on ebay. Super Adepts and etc. Many are well pre ww II. Hobbymats are ok for what they are but as bits can be a bit hard to find best buy one with them and to make sure everything works. Wabeco is very similar only bigger. Some people like Flexispeeds, old and tiny. There is one on ebay with a broken casting, that's what often happens to lathes that have steel running in cast iron bearings and a clamp bolt on one side if they are over adjusted due to lots of wear. I reckon you are correct on losses when something like the 180 is sold but if you go bigger you might want to keep it. Something on the bigger one might break. The ebay Harry person that sells the other lathe you mentioned has an excellent reputation. I know zero about those lathes. Excel have started selling Optimum. A German make made in China. They actually state hardened taper roller bearings on some models. They seem to come with less kit. Excel is in Coventry you will find them on the web. Again I don't know anything about the lathes. The nice thing about lathes with simple taper roller bearing arrangement is that they can be changed and usually use standard bearings. Might need to find some one with a bearing press though. The other aspect is that they are relatively easy to adjust. People like Colchester use several super precision bearings - ouch if they need replacing or can't be adjusted. Trouble with my posts is that it might put some off. I'd hate to do that. Really it's a bit like buying telescopes for the un initiated. Expecting apo performance out of a star travel along with wonderful focusing and huge visual view of mars etc. EQ1 mounts and etc. There used to be an old idea if some one buys a bad scope - sell it on ebay. There are similarities but actually apart from eq1 type aspects I feel lathes aren't so bad if a little sense is used. Also lathes can't be upgraded in the same way some scopes can be so it's more a case of sell and buy another if it doesn't suite. Like an EQ1 they can't really be made significantly better so have to go. Not much chance of changing the focuser on them either. 1/20 wave performance will always cost a lot of money on a lathe unless some one is extremely lucky. John -
  3. There is one thing I didn't mention on lathes of the centre size of the 180 and others. 300mm isn't much when it comes to drilling holes. The usual way of drilling 1in / 25mm holes is to work up to it in stages using blacksmith drills. The shanks on these are 1/2in so can fit in the usual 2 morse drill chucks. People can reckon on having around 100mm left for the 3 jaw chuck and the work. The 3 jaw probably uses up most of that. What it means in practice is a lot more boring to open holes out and also the need for stub drills - once that have been ground so often they are a lot shorter than the were originally or have been ground short purposefully from new. A lot of the space at the drill end is taken up by the drill chuck. Nobody seems to have thought about making very short 2 morse drills to add a few more inches. People might see comments of 18in min centre distance and this area touches on why. That's around 450mm. One thing the Chinese or importers have been known to do is to deliberately shorten the tailstock by cutting off the nose, the bit of the casting that sticks out. That was done to one I had for an extra 2in on the latest model, fine for drilling other than it was 18in before the mod. I had a surprise the first time I turned something that needed a centre in the end - I couldn't turn up to that end of the work, more or less a couple of inches short of it. The suppliers sold me a morse taper extension sleeve - nvg, intended for drills, not very accurate or any where near as rigid as a tail stock. John -
  4. If any one buys HSS tool bits it's worth buying a higher cobalt type as it will hold it's edge for longer. M42 is the highest cobalt content stuff usually about but can be rather expensive. Harry something or the other on ebay sells M35 at very reasonable prices. Often cheaper grades may be around and it's a some what different animal. M35 is sometimes listed at 5% cobalt. Harry's real ebay user name is harryuk123. Looks like his stock is running low ! If HSS lathe tools are kept sharp with a slip stone they will last for a very long time. There isn't any need to visit an off hand grinder again if it's done often enough. Just be careful not to round over the cutting edges. Some people use a linisher for sharpening. That will wear them away more quickly. Or of course a light touch up on a fine off hand grinder wheel. That rustfree oil I mentioned is runny. The slideway oil smells just like vactra so hopefully wont be noticeable in use. John -
  5. The classic designs for this sort of thing usually show a gap between what the pier sits on and the area the observer walks around or sits on to get rid of that source of scope shake. OTT? Don't really know but if you get any shake from that .............................. John -
  6. M&W were budget compared with others Stub. It shows when the mic's are handled mainly - against the likes of Starrett. They don't feel so smooth. M&W do make good accurate stuff though. I have 0-1 and 1-2 in digital. Worst purchase of my life. Used them for a while and found them heavy and cumbersome to use compared with ordinary mic's. That's largely down to trying to get repeatable 1um readings out of them. After a few months I went back to my ordinary mic's. I have some Ford8 or what ever Rotagrip calls himself on Ebay small hole gauges. Cheap and as stated make that size of hole measurement fairly easy but as they are budget the ends of the cone in them might benefit from running a fine stone over them. Pass on his telescopic gauges. One thing to check on mic's. There should be a C spanner to rotate the graduated barrel for setting and also to set the tension in the micrometer thread via a taper nut hidden inside. Revealed by simply completely unscrewing the thimble. Best leave that alone on a new mic but at some point it might need adjusting. I recently bought a medium priced micrometer spindle and had checked that it came with a C spanner. When it came I found that the barrel didn't rotate, it was fixed and no nut to adjust the tightness of the thread. The "feel" when used was set by a grease that had been applied to the thread. Junk really. If some one buys a mic like that the best thing to do is send it back. I'm not sure how many are about that lack the nut. It can be used to calibrate the ratchet but most people who use mic's a lot don't use that as they are not very reliable and use finger grip on the thimble so that they will slip at the correct contact pressure. Nasty as on flat surfaces with every so slightly dirty anvils more pressure is needed so in some ways it's best to clean everything if it matters that much. Not so bad in a lathe as the contact area is a lot less. Easiest way to clean mic anvils is to shut them on some clean paper at the usual tension and just pull the paper out. John -
  7. Depends one how accurate you want to work but I would go for mic's above digital callipers. Boxed sets of mic's usually work out significantly cheaper than buying them one at a time. Decent micrometers will last a lifetime. I prefer no battery, they go flat at the worst possible moment and the digital ones tend to measure to limits that they can't really reliably measure. You can buy cutting oil in small quantities but I bought 5L from here. Intended to be used on steels but it will also help on other materials if needed. http://www.morrislubricantsonline.co.uk/marcia-d-neat-cutting-oil.html As a light smear with brush is sufficient it's likely to last a long time. I use the brushes some £ shops sell that are about 10mm dia. It's best to keep some in a small jar with a lid or a large dropper bottle with cap of ebay. 5 cost a couple of quid. It's worth buying some slideway oil for the lathe. Ebay is probably the easiest place to get that. It hangs around on surfaces so shouldn't need applying often or in large quantities. I sometimes feel that some with a higher viscosity than usual would be even better so will be starting to use this http://www.alexoil.co.uk/waylube-100-slideway-oil--5l_p151.aspx Vactra etc is available with higher viscosity but only in rather large drums. As I sometimes have thing lying around that I should really sell as soon as I can't use them any more I also bought some of their rustfree oil. That plus a plastic bag should prevent problems. It's probably the same type of oil that new tooling comes lightly covered with. On the other hand it might be like bear grease that the Russian seem to coat microscopes with. Bore measurement is very likely to crop up. The cheap option is hole gauges for small one, not used much and telescopic gauges for the larger ones which tend to be ok for holes up to 2 to 3 inches max. There is a knack to using telescope gauges and when set to the bore they would normally be measured with a micrometer. My feeling on callipers is that they are fine on a lathe until some reasonably accurate work needs to be made and that it's easier to take reliable measurements with mic's. If you are going to work in imperial and want to fully exploit the use of an engineers rule the best source I am aware of is ebay USA. 2 types are ideally needed. A narrow semi flexible one and a wider stiff one. Both should have graduation running along the entire length. Not 1in of one and then a switch to another. Some have graduations on the end which can also be useful.. The graduations on them vary but 1/32, ,1/64, 1/10 and 1/100 are available on some each running along the entire length of the rule. This is what an engineers rule should look like. They often don't. 6in is the usual length. Usually made by Starrett. I looked to see if this supplier does anything and they do http://www.mscdirect.co.uk/cgi/insrhm If you want to be sure of good measuring instruments that site might be a good place to go. Personally I wouldn't buy a cheap digital calliper. Their SPI range is probably as good as Mitutoyo and a bit cheaper. It's an odd site to use. Search for what you want and then click on one and then catalogue page. That way you can browse around the sections more easily. Dial callipers are pretty popular, might be an option rather than digital ones. Their sets of value micrometers look very well priced to me. I have used 6in 150mm digital callipers from when they 1st started to appear. Long time ago now. They were pretty accurate according to my ancient Kanon vernier. Can't say the same about one cheaper pair I bought. My old one eventually started miss behaving so after some thought I replaced it with a pair of 8in 200mm ones as I feel that size is more useful. Mitutoyo absolutes. They are sold a bit cheaper than usual on ebay now and again. I have a set of telescopic gauges that I have had for a long time. I bought another larger one as I needed it but have found that it's not as good as my old ones. I suspect it's because the spring out part needs to fit the part it slides in very precisely. As far a mic's go I find my 0-1 and 1-2in are what is used most. I also have a 2-3in and 3-4in bought used. Also as I went metric on a lathe once also a set covering 0 to 75mm. Mitutoyo's as when I bought them as odd as it might sound they were a cheaper brand. These were bought used as well, Actually I think they were ex display and the tool shop just had them lying around for a long time. M&W rule with some people which is probably why the Mit didn't sell. My 0-1 and 1-2 are both by Starrett made in the UK, A bit up market and paid for by the company via a tool bonus when I bought them. Used mic's are generally ok providing they show no signs of have being cleaned up. The engravings should be dead clear - as good as new. They will be if well looked after even if many many years old. It's best to look out for ones that come with calibration standards to set them but often when something is being made the relatives size of parts is what counts. With the Chinese lathes the old rule of add the cost of the lathe again and maybe some more to kit it out as part disappeared because they come with the basic lathe add ons, chucks and steadies etc but measurement isn't cheap. For a surface plate I would suggest a piece of thick float glass on something that is basically flat. Kitchen work surface often is an can make the top for a decent bench too if it's the thicker type. You might find some 1/2in thick glass locally, often now though it's laminated - no use. 10mm should be ok too. John -
  8. I did mention looking to see if ML7's had any shims left the under the bearing caps on the headstock. At least then it might be possible to scrape the spindle bearings back in. Doesn't look like there are any to me which is pretty typical of this particular lathe and spells trouble in terms of finish, accuracy and more difficulty in using it as well. It may be possible to still get replacement phos bronze bearings for it. Probably a little short of £100 but then they have to be scraped by hand to fit the spindle. The original ones were white metal but they stopped producing them. Those needed scraping as well. Been there and done that. The bed wear made the effort needed to do that questionable. I understand some people have managed to cast new white metal bearings in place on the lathe but it must be a pretty difficult thing to do well. I reckon you would be far better of with the Warco and forgetting used lathes especially old ones unless you visit and know what to look for. That Warco is actually a pretty good choice spec wise. I've nosed at it several times and it's the cheapest one they do that I would call a lathe. If you buy I would be very interested in see what they call an accuracy report. You could post a photo of it on here. John -
  9. The only complicated aspect is the lens cell really Ideas will be around on the web and probably in old books too. http://mirrorworkshop.mtbparker.com/refractorStory.html Another but no info on the cell other than push pull screws and a routed mount. http://www.instructables.com/id/Homebuilt-6-F15-Refractor-and-Mount/?ALLSTEPS On good astro telescopes the lens may not be held tightly. Just a really tiny amount of free movement. My 5in F9 apo is like that, a slight rattle can be heard if shook about. If it was tight temperature variations would mess things up anyway. The push pull screws can also be in the cell but I'm not sure how that arrangement works. Some people build the 6in glass blank kits on cloudynights. If a rad comes out a bit incorrect some one is usually about who will run an optimisation on it to correct the error on other surfaces. John -
  10. Millers usually crop up at some point. I did have an earlier version of this one http://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/Milling-Machines/Model-Super-X2-Plus-Mill/SIEG-Super-X2P-HiTorque-Mill It's about in various forms. They have increased the throat somewhat. It used to have a very narrow table but I would hope that doesn't upset it too much. As I may have mentioned I bought it of an embryonic model engineer who I suspect also fancied himself as a machine tool dealer. He didn't rate it all all but 2 points. I suspect he tried to mill with the drill chuck and the slides needed setting. Milling also needs a rigid vice. I'd describe it as cheap and cheerful compared with what could be called a real one or a much much heavier one but set up correctly it was ok. Not brilliant but OK. From memory it may benefit from a cheap digital scale on the quill feed but they may have moved on in that area. There was a counterweight running up and down inside the column on mine to balance the weight of the head - good idea. Just attached to a wire running over a pulley at the top of the column. Setting the vertical slide isn't easy but it can be done by trial and error. The table slides can be set up and polished a bit if needed the usual way - lead screws out and by hand. Has to be said though on any machine a tiny touch tighter may be better. Stiff by hand ?? etc Would I buy one of the other models below this - probably not. John -
  11. On metric it is worth mentioning that it can be more difficult to obtain new imperial measuring instruments now especially in UK / EU. Probably down to retailers reducing their stock inventory. That in itself could swing the decision. Items with a battery in them will generally be dual scale via a push button but battery life can vary a lot. 2nd hand mic's are generally ok but it's best to buy ones that come with a measuring standard just to be sure. In terms of finding them I recently came across this company, all sorts of prices on all sorts of things http://www.mscdirect.co.uk/CGI/INSRCH?Ntt=micrometer&N=4137+4294840511&Ne=180&Ntk=Keyword+Search&Ntx=mode+matchallpartial I started ordering something off them and found some oddities in the catalogue. Cheap stuff though and asked about them. They maintain the descriptions in the catalogue but the items may vary from the images. In the case I noticed it was a DTI stand with a fine adjustment according to the description but the image showed one without. Huge inventory so understandable really. Some of the offers they have are spectacular if you need the item. They came from a recommendation. Cromwell UK is another but their trade prices are well below the catalogue prices. When buying mic's it generally works out cheaper to bite the bullet and buy a set. For digital callipers personally I would stick with Mitutoyo and also buy one which is longer than the usual 150mm / 6in however as this company really is an industrial supplier their value items are probably perfectly ok. Take care on Ebay. Another example of many yesterday. My wife wants a sun shade for the garden. Bought a parasol, £65 on Amazon and £90 odd on ebay. There is more of this sort of thing going on now. It started several years ago. My first that I noticed was stainless kitchen scales at 3 times the price they were being sold for by Maplin of all people. John -
  12. Seeing some one comment on engineering lathes here is the data sheet on a real one. Must add on the cheap. http://www.excelmachinetools.co.uk/products/datasheet/custom/UPDATE_PAGES_28-29.pdf Toolrooms tend to use large lathes. Workshops of one sort or another smaller ones. Frankly I don't think anyone can really tell anything about a lathe by looking at it other than things like the general proportions looking right and if it's possible to turn to the end of work when a centre is in it, Cross slide travel and things like that. If some one lives in the USA there is a bit more choice such as this one that even has the right sort of proportions but I'll bet the gears aren't hardened and that it would probably benefit from a better headstock bearing arrangement which the industrial machine is very likely to have. Just look at the weight. This is more of a workshop lathe. On the cheap. http://www.busybeetools.com/products/lathe-metal-10in-x-18in-3-4-hp-craftex.html Another workshop lathe was the Boxford VSL, Raglans etc etc. In the Raglan days a popular toolroom lathe was a Colchester triumph and even bigger from other makes. Training lathe / workshop a Student. Corner of the shed type workshop a Bantam. Just because some lathes are referred to as toolroom lathes doesn't really mean that they have been used for that much. Especially plain turning ones with no feed. More likely they may have been pre and slightly past wwII. Some toolrooms might have a smaller lathe in there for if they needed to make some accurate parts for other machines. It would be well equipped and most importantly hardly used. My Raglan when I had it had brass swarf in it in places and some slight signs of steel. Probably used by electricians and maybe pipe people in a workshop in a factory some where. They managed to put a noticeable amount of wear in the bed just doing this - right at the very end. John -
  13. If you want to see what Stub does on small kit there is a thread on model-engineer.co.uk called don't do this at home. There is also a thread on tailstock errors on a seig c3. This also shows what Stub did to his. If the guy who is on about the tailstock error is correct it's not too bad at all really. If you read it you will notice I am not too happy with how he determined this and suggested how he should go about it. The truth is though for most work a 0.005in height error would give a slight increase in dia towards the tailstock - easily corrected by a slight but difficult adjustment of the tailstock off set. Not really worth worrying about for lots of work. The thread is called tailstock and stiff handle or something like that. The problem is though that as often is the case certain things have been read on the web and he wont do what is needed to really see what the lathe is doing. Pity as that would give an idea just how good or bad these lathes are. As it is he is lapping the base of the tailstock and the outcome might be nothing like he expects. If the errors on the centres are minor there are much easier fixes. Seems some one has invented a new name for a DTI. I also came across a go to bar recently and assumed it was something virtual written in dartmouth basic. I feel some are trying to make machining less understandable by changing the names of things to something meaningless. The model engineer site is some what commercial so there is always the chance that things aren't as they seem. However I asked how some stainless steel work had been finished as so and so gives great results. Where there were answers files and emery cloth. Any old lathe will do that. When considering lathes that aspect has to be remembered - filing rests have been very popular at times for producing parallel work. Wonder why they have been designed for Myfords. It's hard to know what to advise some one who is considering buying a lathe to do other than don't rush and point out the problems. Perhaps the best answer is to buy and find out. Even a C3 has a 2nd hand value. There are still local model engineer groups about. That could help but there will still be people about who will sell any old thing without warnings. I don't think ebay is usually a good place to go for lathes especially cheap ones with little or no kit. To many people about who just must buy a lathe, Many who don't really know what they are doing. People might find themselves paying a couple of hundred quid for something that was found on a scrap heap. I tried buying one like that once but set a limit of £50 and got it. Few would be interested in a plain lathe of it's size, a Boley with some rust. Not too difficult to get rid of that. And it did come of a scrap heap. John -
  14. Talking refracting telescopes and tubes I had reasons for mentioning getting nice square ends on drain pipe on a Peatol / Taig. The limitation is how large a diameter can go through the fixed steady and when metal fingers are used on those it's not a bad idea to modify them slightly by adding a small ball race to the ends of them. The tube is best gripped with the outsides of the usual 3 jaw chuck jaws or the 4 jaw if it's to be set central. It might distort the tube depending on thickness. Have enough spare past the chuck to prevent that being a problem. There will be no tailstock on the lathe so the tube can be as long as required but at some point a support could be added - say a V in some piece of wood. The inside of the tube can't be bored. The outside can be turned within the length between the chuck and fixed steady. The whole tube can be polished but the steady may need moving along at some point. The outside of the tube can be screw cut if needed. When finished just part the wanted piece off leaving some on the chuck. The travelling steady can be used too which depending on design will prevent the tube from tipping when it is parted off if a bit of pressure is applied to hold it in it while the fixed steady supports it. Some sort of lathe external support could be used as well. When it's parted off the outer cut will be square and clean. The inside may have some fraise easily removed with a deburring tool. When I did some drain pipe I just supported it with my hand and the fixed steady - smooth dia etc well away from the parting tool and nothing to catch fingers on. There are other ways of holding the tube. Turn up something to be a firm fit in the bore of the tube. A slight taper can help. Tap the tube onto it, square the end with a parting tool, do what ever to the tube and when finished tap it out. This is the sort of thing that might be done on to a morse taper arbour if some one wanted to make a lot. Fixed steadies are very useful. They can also be used to do work on each end of pieces of bar the can't be fitted on the lathe but parting off gets more tricky. The bar will need additional support. John -
  15. LOL if you obtained your dream machines you could well be disappointed. I did have a Schaublin for a while to resurrect. Proved to be too problematic so sold in bits. In order to get some information on it I joined the schaublin group who were very helpful. Most had larger ones that use more complex rolling bearing arrangements. This was the group that suggested I tried the tips I posted earlier when this sort of thing was discussed. All of them do excellent work but several of them were impressed with the finish I could get on silver steel on my Boxford. Some had excellent machines with no wear, virtually new. Totally different animal and the bearings for them are very very expensive so there is a need to have rather a lot of cash about if that needs fixing. The problem with lathes is that people buy them to use and bearing wear far more than people might think if they are used daily for long periods. Beds too. I wondered about a BCA borer too - such a name that silly money comes out just like it does on worn Schaublins. It would be nice to have the fancy bit that goes on the bed of some of these borers - I could stick it on my miller. Lathes linked to Early Unimat - think clock making on the cheap. That needs a lot of generally expensive bits and pieces if you fancy doing it. Smart and Brown - that's a collet lathe and a very old one. Don't know what type of head stock bearing it will use. Collets are wonderful for some things but chucks are far more useful and may be a problem to find or fit on that one. That sort of lathe at that age could well have been used daily for 5 1/2 days a week some where. Emco - that sort of milling arrangement can be useful but usually a small miller is a better option. Lathe - pass depends on a lot of things such as wear and tear. It probably uses standard sized bearings in the headstock so they could be replaced. It might not. The only way to tell really what is what with them is to use them and to be really sure take some tools, a mic and some steel with you. Much the same with any machine. For some reason it's missing it's 4 jaw - unusual. A lathe of this make might have had a fairly easy life. There are tools with it which may have been made on it. Some possibility that this is a good sign. If you post a link to a lathe I don't think anyone will say buy it. John -
  16. Not precisely. When cutting metric threads some pitches mean never disengaging the screw cutting so when a thread cutting pass is at the end the lathe has to be turned off and then run back to the start by running the lathe in reverse. If there is no screw cutting indicator may as well say that this always has to be done and it's a very slow process. If there is one the ability to use it depends on how complex it is and the pitch of the thread that is being cut. Some will be ok with more pitches than others. I tried to explain why this happens. Switch to an imperial screw cutting lathe with a screw cutting indicator and common pitches, a very wide range of them in other words can be cut by disengaging screw cutting and winding back to the start by hand and then re engaging using the indicator. Fit gears to cut metric threads and it will be the same as a metric lathe with no indicator but I explained how the indicator can help screw cut up to a shoulder. Also more recently how to screw cut with these when there is no indicator. That is the same on either style of lathe metric or imperial when there is no indicator. There are more variations. Some fit a large handle on the end of the lead screw - they cut coarse pitches by turning it by hand or any pitch they feel uncomfortable with the speed the lathe is running at. This also helps to cut up to a shoulder. Some might even cut with the lathe and wind back with a handle. There is one other area that makes me stick to imperial machines that may not apply to smaller ones and that's the graduations on the dials. It's back to King Henry's thumb again. By some fluke 1/1000 of it's width happens to be a very practical graduation for a machine. It's even possible to judge small fractions of them accurately. It just happens that this works out with lead screws that have a sensible pitch that wont wear out too quickly. The graduations on metric lathes are often a lot coarser due to the physical length of a mm. On small lathes they tend to use smaller pitched lead screws which will get round this aspect but often on larger stuff they don't. I need the accuracy some times. Curiously the same thing applies to measuring instruments. A mic for instance can measure with some hope of giving a real reading down to 1/10,000 via a vernier scale. The answer on metric is to go digital and supposedly go to 0.001mm. 2 facts, measuring to that accuracy with simple gear isn't that simple and to try and do it the mic's get cumbersome to use. A metric mechanical mike can measure reliably via it's vernier if it has one but the units are odd. I often feel this must all be anthropic - some round here will probably know what I mean. The other weird thing is that I can measure with an imperial engineers rule to better than 0.005in. Those have to be bought from the USA these days. There were some attempts to get round this area. I came across some metric Boxfords. The cross slide lead screws had a 1.5mm pitch. I suspect they may have been specials for schools. I was around toolrooms and drawing offices when some were metricated. It caused an extra ordinary number of problems all over. This included fitting dual scale dials to machines. Real fun to use because there had to be gap in the metric scale. Some how I suspect this whole area has led to a vast increase in the sale of digital readouts once these had been introduced. Actually I am perfectly comfortable working with either system and true in some areas metric units make the sums especially a lot easier. I'm not convinced this is the case when machining so have stuck mostly to imperial. I have had metric lathes. Other than where I have mentioned it makes no difference really. John -
  17. Can't remember what the minimum speed was but I have screw cut on Hobbymat. It's not too bad if the pitch isn't too coarse. The thread was whatever UNF size is used to attach electric drill chucks. Emco items tend to be a bit expensive when they can be found so I found a cheap morse taper reamer to fit the tailstock and parted off enough to make a morse taper arbour. Turned to the correct diameter and then screw cut it. This was up to a shoulder. That meant that I had to have a gap at the end of the thread to the shoulder that was big enough to allow the lathe to stop when it was turned off without the tool hitting the shoulder. Fortunately lathes stop pretty quickly when screw cutting is engaged. Easy to find out how much space is needed - just try it without taking a cut. Sometimes it's possible to turn a short section at the end of the thread that is below the root diameter of the thread being cut even just using the screw cutting tool. Saves having to wind the tool out when the lathe is being turned off. It can be useful when cutting internal threads as well because the sound from the lathe will change when the tool enters the recess. I thought Myford Super 7 and ML7 lust might crop up. Most of their fame really is down to commercial interests - all of the things that have been designed to be made on them and the publicity that gives. In real terms they are budget lathes of their day with the attraction of being relatively light for their size. They can have all sorts of problems and can also be incredibly good in terms of surface finish especially the Super 7 but unfortunately some parts wear rather rapidly if they are used a lot and also as is often the case not that well maintained. The lathe bed is a very poor design really even of it's type, that causes a lot of the problems. ML7's need shims available under bearing caps so that they can be rescraped when needed. Adjusting a Super 7 headstock to achieve what they are capable of is very difficult and wear is likely to prevent that anyway. ML7's for some people are more popular as they can drill bigger holes than a typical Super 7 - the headstock on those really is tricky to set up. I owned one of those 3 in 1's too. Mills and drills after a fashion, turns a good finish if adjusted correctly but the general alignment of things was awful. I spent some time trying to sort it out, got very annoyed with the suppliers, water off a ducks back and sold it on very honestly to a garage owner who wanted to impress his customers and the main requirement was shortening bolts. I still used the supplier when I had too and looked at a used Super 7 they had just got in. For some reason they decided to be honest with me this time - the previous owner made model aircraft engines on it so it MAY be ok. The chances are that the engines were sold on and the lathe had been used a lot. Could be it was time for another. He had obviously made a lot of them. I also came across a Boxford locally. Home turner who made a living doing batch work at home. Time to get another one due to wear even though the tolerance requirements on parts like that are pretty low as people who put that sort of work out generally don't expect much from a lathe. A lot of this sort of thing has gone on using cheaper semi pro machines for a long long time which is why they can be so bad generally. Home machinists are also seen as easy picking by some. There are all sorts of dealers about even some that look like they are model engineers. Some are. My 1st milling machine was a barely used Chinese. My 2nd was a Dore Westbury. Both owners thought that the machines were hopeless The 1st one just needed adjusting correctly. The next owner was very happy with it, I phoned to check as forgot to give him the manual. The DW was risky, they are sort of home made but the work looked to be of a very high standard so I risked it. He demo'd it end milling with a slot drill, poorly adjusted and using a vice that just isn't up to milling. Interesting machines. I've come across a few people with them, all seem happy. Might be because anyone who took on actually making one would need to be pretty skilled to even try. I'd guess in my case a retired toolmaker. There's basically no easy route to home machining that doesn't have it's risks. I'd have saved some money if I had listened to my father. Metal removal was his expertise. He asked me what lathes they had at school. I had used one of them and noted the make next time I went into the metal work shop. Boxford, comment those aren't bad they are based on an American Southbend. His idea of a good small lathe was a fully equipped CVA. If only, the head is probably 1/2 the length of a Myford but they are short for this sort of thing. Equipment would be a problem too. He was also looking for several lathes to fit into vans to go to various motor racing meetings and the people who went asked if they could have Myfords so he went there for a demo. He was very impressed with the finish they obtained on a super 7. As this sort of thing was his business he took a look at the headstock bearing arrangement and told me that it was down to the huge cone bearing they used at the front. And then added I'll bet they adjusted it just before I arrived and also had run it for some time. I'll add that Myford may have had a source of good quality free cutting mild steel in black bar as well. If it can be found it is way better than bright bar. He bought Chipmasters instead 2 reason, bearings and also that the people who would be using them would break several things on Myfords especially the T slots if they use them. Wish I new what millers he had put in them. Probably too big for me anyway. Are Boxfords great - no but my feeling is that lathes that use a headstock with rolling type bearings in it and a fairly sensible bed design have fewer problems than others. I could tell other hard factual tales about Myfords but it wouldn't serve any useful purpose. There can be problems what ever any one buys and lightly used machines are not that easy to find. John -
  18. Pultra abuse if the same problem crops up again. I mean I have 40mm riser blocks for it giving a swing of 180mm plus and an incredibly high tool post. Should be able to use 1in HSS in that. It mated with something else over night and 17/70 appeared so the blocks on that would give a 220mm swing and an even taller tool post. They are both variants that don't appear on lathes co uk nor in the usual pultra manuals. People need to realise on swing etc that the main thing is not to overload the motor or don't load it any more than they usually do. Bigger stuff needs lighter cuts and that's all. Get it correct and the load is no different to what it would be at smaller sizes. With big slabs like the one shown balance is also important as lack could shake the lathe to bits - as could smaller bits. In fact when certain types of things are made on a face plate weight has to be added to keep it all balanced. It's a bit like balancing a telescope - but best arrange the spindle to be completely free some how. This area touches on why face plates are sometimes bigger than anything else that fits one the spindle - so that work can be done when it isn't all central to the axis. It's really a better option than a 4 jaw then as the work can be balanced. John -
  19. LOL I have a feeling I know who Stub is now. One more thing on adjusting bearings. From the arc details on sprucing up a C3 it looks like it has a common problem with bearing fit. The bearings and spindle have to be made to some suitable tolerance. An interference fit in this case that will vary. Trying to produce a light interference fit is a challenge but some lathes will have one. My boxford was super tight I thought I would never get it out but did eventually. Before putting it back I stuck it on a Peatol and got the lapping sticks and honing oil out There's a need to use a mic with extreme care. Perhaps the best way to adjust bearings due to this sort of thing is what I did before loosening the rear one a bit. Put the C spanner on and tap some tiny fraction of a turn with a hammer if a lot of effort is needed to turn it which I suspect is likely in many cases. This also means that once over tightened they might not release that easily so tighten very very slowly. Just a tale on cuts. It can be surprising what even low powered lathes can do. While sorting out a Raglan I dropped a cast iron pulley about 3 to 4in diameter onto concrete and broke a corner off it. I mounted it into a Peatol and turned that rim off completely and then made mild steel annulus to replace the missing side of the V groove. Wanting to make sure that it ran true I then fixed it to the pulley and mounted it on a turned mandrel to turn the replacement side of the V Couldn't use the compound slide but just managed to get a angled form tool in. Poor old Peatol finished up taking 3/4in cuts with nice shiny curls of swarf coming off. Didn't do the lathe much good as it bent the head but it did it helped because the in feed was very slow so. Just goes to show that apart from that sort of problem what a tiny lathe can do if it's set up correctly and rigid in the right way. They are pretty good actually but the head will bend over time. They will work to well sub 0.0005in all round tolerance till that happens. Swarf also gets on the rack due to where it's positioned. Like Unimat's though size and other things are a real limitation. They are great for getting nice square tidy ends on drain pipes with most of the length sticking out of the back door. John -
  20. I'm spending too much time on the web but suppose I could explain the metric thread problem. Some one explained the maths to me a long time ago in a lecture but I don't have the notes. If some one does I'd appreciate it. From memory it uses radians / sec which cancel out. The lead screw and the work are usually rotating at different rates and the lead screw has a thread on it. When screw cutting is engaged the saddle moves along and cuts a spiral at some pitch according to the relationships. So get to the end of where the thread has to be cut and disengage screw cutting. Wind the tool out and wind the saddle back to the start, re engage screw cutting again. The problem is that there is no guarantee that the tool will travel down the same spiral again. It will if the lathe is set up to cut the same pitch as the one on the lead screw. I have heard that there are others but suspect that is confusing something else. A screw cutting indicator is a gear that meshes with the lead screw side on with a dial on top of it so the dial rotates as the lead screw rotates and also when the saddle is moved when screw cutting is dis engaged. So this time when a thread is being cut screw cutting is engaged according to the marks on the dial. That ensures that it will go straight in rather than riding on top of the thread on the lead screw but it doesn't something else as well. It's indicating the rotational angle of the lead screw. Get to the end of the thread and disengage and the dial will then start rotating again indicating the current rotational angle. Wind back to the start and as it's still meshed with the lead screw it will continue to indicate it. It remains in sync. Then when another cut is taken the tool will travel down exactly the same spiral as it did before if the same mark on the indicator is used. Actually there are some rules. Some thread pitches could be engaged on any mark, some on every other one and some on just one. How far that goes depends on the design of the indicator. I suspect some knowledge in that area has been lost as I have cut threads on one lathe this way that wouldn't be possible on any other lathe I am aware of. If there isn't an indicator or it can't cope a different technique can be used. The usual one is to wind out the tool and stop the machine at the same time at the end of the cut. Select reverse and run the saddle back to the start again. As screw cutting is never disengaged it will always be in sync. It's not much fun screw cutting up to a shoulder. It's still possible to make good use of an indicator when threads are cut this way. Sounds hard but it isn't. At the end of the cut note where the indicator is, wind out, disengage the screw cutting and turn off the lathe. Select reverse and engage screw cutting when the indicator is back where it was when you disengaged. Much easier to work up to a shoulder this way. It works because the lead screw is highly unlikely to revolve enough times for it to loose sync when the lathe turns off. Actually it would be extremely unlikely to revolve too much to prevent this from working due to the relationship of pitches that need this and lead screw pitches. Imperial threads are based on TPI as are lead screws. The important thing is threads per inch. This means that there can always be a sensible fractional ratio between leadscrews and commonly used pitches. This means that the usual thread cutting indicator with 8 marks on the dial can be used to cut all of them. This is how the pitches were chosen to make that so. There may be odd ball ones on pipes, gas fitting etc but little else. This comes about because the pitches used have a simple fractional basis. Try dividing common metric pitches with each other and you will see what I mean. They have more than one "base". And when cut on an imperial lathe they have no common base at all. To be honest I have hardly ever seen a metric lathe with a screw cutting indicator. Where I have they tend to have more than one gear available to mesh with the lead screw. Myford came up with one gear that will do some useful pitches on the ML10. Colchester did an amazing one, more gears and then comes another problem - the time it takes for the indicating marks to come round on some pitches. This comes down to how often the pitch being cut divides exactly into a number of lead screw pitches. It has to do that for indicators to work. The answer is probably never when metric is cut on an imperial machine via conversion gears or some number that is absolutely enormous before it gets insignificant - help with the screw cut indicator disengage method. This probably comes about because our impoverished European neighbours lacked King Henry's thumb as a base measurement and probably were not keen on choosing teeth per cm as it isn't long enough to give enough numbers. Teeth per metre would be a bit weird. They picked pitches like topsy, same as out BA threads which are sort of metric and aimed at instrumentation work not engineering. An instructor once said to me after enquiring what metric fine was about said forget it as metric coarse is too fine really, what do you expect they are basically a bunch of watch makers. There is some truth in this. BSW/UNC into aluminium should be sadly missed if it disappears and other materials too. It was aimed at iron. BSF at steel. If any one finds a real list of what have been standard metric threads they would be gob smacked at the range - yet more pitches to get round the problems. Seeing what has popped up since starting this post and doing one or two other things too I would still say investigate bearing heat what ever is fitted. The question is how much heat. Can't help there. To me there is little difference between angular contact and deep groove really as deep groove will wear to only running on one side just as angular contact will. I feel that the best option is to try and keep them adjusted but at some point they will have to be replaced. Grease - not much at all and it does cause problems with adjustment as it has to settle down and takes a lot of effort to displace. Turning is good at doing that - some decent hefty cuts as big as the lathe can take. Drilling max capacity holes in mild steel is good too. The nut on the end isn't so good. Cutting pressures will get the front bearings seated and loosen the rear which is at least a start. I found i had to set the ones on my Boxford several times. I suspect like the Boxford method and also feeling for drag that this will only work with new bearings as supplied are fitted and before they are greased. I started on the heat route because some one who should know told me that lathe bearings run at over 100C. These are big lathes and the front of the headstock on these does get rather warm. There is also sometimes an improvement in finish too. The spindle warms and expands where as the heat in the outer shells of the bearings remain cooler as heat is taken away by the head stock casting. That's my theory anyway and is why I mentioned 20min. 10 will probably do really. John -
  21. Sounds to me like you might need to do some work on your slides Gina and also the headstock bearings. It's best to set the gibs on the slides with the lead screws out and look for slight drag when pushed by hand. Might be worth checking for sharp corners fouling too. I've also lapped slides a little at times using a mix of CIF kitchen cream and oil. It wont cure errors of any significant size but it can make things run smoother. It's a case of keeping on adjusting the gibs and sliding back and forth by hand while thinking about keeping the "wear" even. It's well worth buying some Vactra slideway oil as well. It has been on Ebay in smaller quantities but there are also web sources. I can't give specific instructions on setting the head stock bearings but have the problem on my Boxford. They give very specific instructions but it doesn't work out. The bearings need to be preloaded and the question is how much. Boxford state stick a face plate on fix some rope etc to it and pull with spring balance and set for so and so. Initial stiction messes it up but even accounting for that it leaves them too loose. The fact that the bearings are pre loaded means that there is friction. Friction means things warm up. What I do is run the lathe for 20min after an adjustment at a medium speed and feel the heat in the area under the rear bearing with a finger via the spindle bore. I expect it to be cosey warm. I never run my lathe flat out but if people do best check at that speed too. It will be hotter. The end result is that I can see a slight improvement in finish after the lathe has warmed up. Even grease and moderate warmth can still mean that the bearings are loose. One way of telling is to take a cut and wind back along the work at the same setting. If more is taken of the spindle is moving via the bearings or the bar has bent. It's best to make it a decent cut in say a 1 1/2 in of 1in OD mild steel. AFTER the slides have been set as on some lathes looseness there can cause similar problems especially if the saddle is not seated well. The reason I mention this is that bits shouldn't fly off. The worst offender I had was an ML7 whose bearings were shot, all that kept the spindle in place was tension from the belt. It was also brilliant at chipping carbide tools. Things don't dig in if the lathe is set up correctly and most materials should produce nice strings of swarf to such an extent that it has to be pulled off with a swarf hook. People often buy 6in grinders. Much to my amazement as much larger wheels are usually reckoned to produce better results Axminster sell some white aluminium wheels that make an excellent job of HSS. HSS tools really need polishing after grinding though as the finish on them will be transferred to the work. Arceuro sell some diamond lapping stick that could be used, best add a bit of oil such as 3in1. It also best to put the radius on the tool this way unless some one has high off hand grinding skills. A rad on the tool distorts the metal and promotes tearing and only needs to big in comparison with the feed that is being used. It's hard to achieve that on an off hand grinder. The other point is that the lapping sticks can be used to resharpen the tools periodically without even removing them from the lathe. When doing this and also polishing them it needs to be done in a way that wont radius the cutting edges. That just need a bit of thought - working up and down on the cutting edge might just do that for instance. Do this regularly and tools last "for ever" and only get ground once. As astronomers are rich or so people tell me it might be worth mentioning carbide especially disposable tips. I use one of these from time to time The holder is out of one of those cheap sets off ebay. Wish I could get this one singly. The tips that come with them are so so and if bought make sure that they come with Torx screws as the hex keys soon wear out. The tip on it is an 1100xxxx series 11mm from APT that was listed for finishing stainless. They also do them for aluminium. The stainless ones work well on most things but the aluminium ones will improve aluminium. APT also sell their own brand of holder for these, a turning and facing type but the smallest one might be too big for lathes like the C3. While opinions vary some including me reckon this type is as good as can be bought for small lathes even up to Boxford size. Like them I have tried a number of types at one time or the other. Brazed tip carbide tools can also be sharpened - just buy a green grit wheel for the grinder. They can't have the sort of rake that is on the tips though and if clearance angles are pushed past some point they will chip. I used to grind up brazed tip paring off tools for screw cutting. I usually use HSS chasers now as I have them. There is an interesting grinder about at the moment made by Ferm. Same as one by Record but a lot cheaper if bought off Amazon. It has one white wheel and is because of that wheel more suitable for converting to a lathe tool grinder IF PEOPLE ARE FULLY AWARE OF WHAT THEY ARE DOING. The sides of wheels can only be used for light touching up. Oddly 6in grinders run at the right sort of speed for 6in diamond wheels but frankly I feel that they are a bit of a waste of money for little gain really. They might be worth having if super fine grades were about to save polishing. If a C3 goes down to 20 rpm or even 50 it would be the one I would buy because Arceuro really try hard. I buy all sorts of things off them and haven't been disappointed yet. Can't say the same about RGD. I also visited Chester once to help a friend choose a lathe. I suppose they are all the same really but after mentioning a couple of things they didn't have anything available that would suite me. The friend ignored the advice mostly due to demo type web sites and weight of machines and regretted it. He went for the baby size though. There is a guy trying to make a C3 super accurate at the moment - read things on the web and wont even make a between centre test bar to help him be sure of what he is about to do. Or even turn up a few bits of bar to see what the lathe is actually doing. Good luck is all I can say. Meant to also mention another useful item. A hammer headed diamond grinding wheel dresser Axminster sell. It makes dressing easy and so far has lasted well for me. The white wheels don't need it any where near as often as others though. They are friable enough to remain sharp. John -
  22. One thing that should be noticed on Arceuro's sieg c3 is the upgrade section but on the other hand the chester DB7VS comes with the bits most people need and goes to a lower speed. None of the lathes mentioned have a screw cutting indicator which is a bit of a pain. This seems to be because they tend to use lead screws with a pitch of about 16 tpi rather than 8. Looking at the DB7 there is another common silly. Swing over the bed quoted at 180mm were as the cross slide limits facing to 150mm, less in practice. Some one mention distance between centres and drilling. True. An old idea of a useful min distance between centres is 18in, bit short of 500mm. This is why they reduce the head size on the next larger size - to get it in and still keep the lathe small. The other old rule was for 1in bar to pass through the spindle. Not really possible to obtain but believe it or not the odd Eastern lathe did crop up with that and then disappeared. Only in the USA though. One old lathe that might interest you is the Myford ML10 or better still Speed 10. In some ways it's Myfords usual design disaster from a purists point of view but they are likely to be a lot less troublesome than the 7's. You will be able to pick one of those up but it will be a bit of a struggle. It will be a lot less of a problem with tailstock, head and motor removed. They are around 3ft long. You will get the usual lathe facilities with one of these including a back gear and there are plenty of spares around for them. One nice thing is that the bearings can be changed more easily than other Myfords but there may be a need to find some one with a bearing press. They use taper roller bearings. Some of them wont have had too hard a life as they are mostly a model engineer lathe. That isn't the case with the older smaller ML's. They might have even been used as a capstan day in and day out at some point in their lives. Curiously the metric version of 10's does have a screw cutting indicator that can be used on some pitches. Change wheels are available for cutting metric on imperial lathes as well but the lathe will have to be reversed at the end of each cut - as it will on some metric pitches on a metric lathe. Myfords are budget real lathes really and looked at that way the 10's are a clever design to keep costs down. Current prices for new 7's are basically stupid, no one in their right mind would spend that much on one but no doubt a few might. As I see it astro bits are likely to need screw cutting - adapters and things like that but most other screw cutting is done with taps and dies. As I see it if you want to do the lot it would be best to go for a lathe that includes a screw cutting indicator so maybe it would be best to re arrange your shed a bit. One thing I feel is very important when buying a lathe is don't rush. The other thing to remember is that buying bits an pieces for lathes is a money pit so it's best to buy with at least the basics are included or to at least look and realise what adding them will cost. The essentials as I see it are 3 jaw, 4 jaw, change wheels if needed and a fixed steady plus probably a face plate. Then there is a drill chuck and revolving centre and in the end for most a quick change tool post with a few holders. Actually as a 1st lathe I suspect that a decent ML10 would suite you rather well but personally I wouldn't touch one unless it came with it's change wheels as buying them individually would push the price up even as cheap as they are on Ebay but having to buy a couple isn't too bad. They do crop up on ebay from time to time. Maybe a wanted add on homeworkshop.org might turn one up. I'd guess that a new fixed steady would be a bit of an arm and a leg price and it might be hard to find one. One possible problem. They are used when doing things like boring long tubes or doing things to the end of long work even just facing and centring. As stupid as it might sound for light work one could be made out of a mix of MDF and metal for the fingers, brass would do. It's also possible to route aluminium with normal carbide tipped woodworking cutters if light cuts are taken. The router cutters aluminium window frame people used might still be about too. The Peatol / Taig lathe uses a very simple design that works. There vertical slide is excellent too even though it's a bit small. It can be adapted to fit most things by adding a plate. One problem with wanted adds is the crooks. Beware of super shiny freshly painted stuff. Lathes tarnish. Another place where used lathes can be found is lathes.co.uk. There are also a number of dealers around but generally they sell the lathe without bits and pieces as they make more money that way. Might be worth looking at homeworkshop.org.uk too. Gumtree, Preloved, local ones etc. Failing that I suspect a re arranged shed and the bigger chester is the best bet. It doesn't look like a 918 to me, nothing like it. Those are from the days when most of the lathes the East did looked to be pretty sensible all round. Maybe one of those plastic thingies to keep the lawn mover in etc would help. A used one of those might be about. I have no idea just how good these lathes are. I went Chinese once and never again currently but I understand that with a bit of titivating they are a lot better now. When I bought my Boxford I asked the person selling it to turn 6in of bar with no centre in and measure the taper. He reckonned it was 0.002in. A photo of the finish wouldn't have been a bad idea The taper turned out to be less than that, the bearings needed adjusting which would also spoil the finish and bars bend a bit when turned like that. It was on ebay with a reserve. At the time no one would pay more than about £500 for a Boxford. This one had lots of bits with it so I valued it on that basis. The bidding stopped at around £500 or so and I placed a bid of £1000 a few seconds before the end of the auction and got it for £700 which was his reserve price. A bargain really especially for me as it was rear drive and I have to have a bench lathe. Often when well equipped lathes turn up people wont pay what they are worth. I had a brief interest in a Cowell's recently and one with all of it's bits and pieces turned up. It would cost well over 2k to buy new and it went for £800 - I went to look at it and it was in excellent order. Biggest problem really is that the lathe new sells at what is really a silly price for what it is so I bought something else instead but waited for the right machine to turn up. It would sell on Ebay for a lot more than I paid for it. Over all message really is don't rush, that's easy to do if the money is about and also to think carefully. There are always several options in areas like this. Just hope that if you or anyone else does buy an ML or Speed 10 it does turn out to be a decent one. On the other hand if resold little if any money will be lost and it is also worth spending more on lathes like these to fix them up if needed. The other problem with mentioning things like this on the web is that it often pushes prices up. Been there and done that so now keep ultra quiet if I'm buying something. John -
  23. I don't know if it will handle the size of work you want but Siege C3's are popular and going on the errors some one has just found on a new one for what they cost it isn't bad at all. Arceuro sell them. A company that does try hard like Harrry??? on ebay. I feel it's a bit small for you though. People also spend time sorting them out. Arceuro have a nice detailed leaflet on that here http://www.arceurotrade.co.uk/projects/prepguides/C3%20Mini-Lathe%20Preparation%20Guide.pdf This doesn't include such things as lapping the tailstock casting if it happens to be out and you need it to be precise. For 4in diameter work I feel you should be looking for a lathe that comes with a 5in 3 jaw. The 4 jaw is likely to be bigger. I feel that the makers give a better idea of the real capacity of the lathe this way than quoted centre heights etc but this doesn't mean you will be able to take huge cuts at that diameter. Do make sure that the work you will want to do will pass over the cross slide. One problem is that lathes like this are likely to weigh circa 100kg, probably more. As do Myford's actually but buying used Myfords can be a very disappointing experience. It's a mine field. Used lathes generally can be. People get round the weight problem by dismantling them. People also use files and emery cloth or what ever to get round accuracy problems. A lathe with a 4in 3 jaw might come with a 5in 4 jaw. That will hold 4in dia work firmly and if aluminium it cuts pretty easily compared with steels. Screw cutting anything other than rather fine threads when lathes can only go down to 100 rpm isn't much fun but if people stick to what is basically an imperial lathe and it has a screw cutting indicator it helps. It can also help cutting metric threads when the lathe has to be reversed at the end of each cut. If some one is making something for themselves it doesn't really matter if imperil threads are used. It's pretty common for metric lathes to have no screw cutting indicator. Some do but they tend to have 2 gears which can be fitted to mesh with the leadscrew and unevenly spaced divisions. One of the reasons I mentioned the C3 is that it has a sane looking headstock. Sounds silly but imagine when the holes for the bearings are made and there is say 0.001in error. If the head is 4in thick that's how much taper it will turn on work over 4in. If say it's 10in thick the distance goes up. Bearing errors will add to this as well. Looks like the 920 mentioned also has a decent depth of head but it's hard to be sure without physically looking at one. All real lathes have long heads for this very reason. The bigdog link on the 920 page mentions how low the run out of the bore of the spindle is - this only means anything when work is being turned between centres. The axial alignment of the head is the important thing and never mentioned. He also seems to be showing metric dials and imperial screw cutting ???? but it does have a screw cutting indicator. It will also go to a lower speed than the C3. Mention of 3in chucks too. One problem with bigger lathes is what happens to the price. This one will be about under other names http://www.warco.co.uk/metal-lathes-metalworking-lathe-machine/17-wm-250-variable-speed-lathe.html Weight and price goes up but it does come with the bits people are likely to need 3 jaw, 4 jaw, fixed steady and a face plate which can have it's uses at times. Some lathes have T slotted cross slides. They can come in useful on hobby machines. I'd guess they are thin on the ground because they restrict the swing over the cross slide a bit and cost more money to make. The heads get thinner to increase the distance between centres. Sometimes the tailstock is too short to allow work be turned up right to the end when there is a centre in it - same reason. Sorry if this doesn't help your choice much but at least it might give you an idea what to look for. Apart from a Hobbymatt, a Unimat and a Peatol / Taig I have stuck to used machines. The head on the Peatol bent a bit eventually, it was very precise when it came, swarf also gets on the rack. Hobbymatts aren't too bad but need checking over carefully and if the original tool holder is over tightened the casting will crack. The unimatt is a different sort of machine. I did have a fair sized chinese lathe at one point - hopeless in respect to alignment but they may well have improved since then. It was the lathe with a sort of miller bolted to the top of the head - bad idea. I sold it to some one with a garage that just wanted to shorten bolts. I'd guess you need to step back from 4in dia really. It's not a bad idea to have a small lathe about that doesn't take up much space even when you have a larger one. Making bits for the bigger one for instance. I have had my Boxford spindle on a Peatol. Sold but if the same sort of problem crops up I have another small lathe now. Do try and get one with all of the needed bits though. Costs shoot up when bought separately. Sorry I haven't read Gina's thread so can't comment. John -
  24. There is a difference when you are doing that Nigel - you can see from the testing you do where glass needs removing as per the Palomar mirror. There is also the brave way - forget the sphere and go for the parabola. Trouble is when surfaces start going up and down probably even with slopes in different directions it can be very difficult to see what needs to be done. One problem Damian has is that he can't actually measure how much glass needs to be removed. He could try taking measurements and sticking them into some software and setting the conic to zero. I would say exactly the same as before - if a small lap is used or just one area of the mirror is worked because of the size of the lap do spend some time blending for each session. The blending in this case will still lower the hill. Same with the earlier work further out from the centre - do it often enough and no hill. As to back stepping - just thought that it had to mentioned and would be surprised if others were not thinking the same thing. It's much nicer to have some measurements to base that decision on though - if they can be taken well enough and that can be tough. John -
  25. Blanks are never junked unless they are dropped etc and broken. Seems I am rude because I pointed out that Damian has spent more than enough time to finish this mirror. Comment made because I am annoyed that he is having such a bad experience. It could put others off having a go. Anyway as my comments are not appreciated and making another wont do any harm there comes a stage in mirror making where things have gone wrong and the only and quickest answer is to back step - even when forming the parabola. In that case it's working it back to a sphere again or at least part way. Turned edges can mean going back to fine grinding as there may be too much glass to remove with a lap. Other defects can mean the same thing even a hole in the middle as that means a huge area of glass has to be lowered just like with a seriously turned edge. Actually going back is beneficial as people then know that what they did at the next stage didn't work out and can hopefully react accordingly. Personally I think Damian has 2 problems. Pitch hardness and lap size. The lap is about the right size for forming a parabola on a mirror of this size. Good for lowering the centre region and working down towards the edge. From the description it's also pretty light if made from wood. If I remember correctly John advocates concrete - I'd seal it with diluted water proof pva or diluted exterior grade wood glue - same stuff. Pressing down on a lap to make it work like a heavier one can't be a good idea as it will be impossible to apply an even pressure. Personally I feel it's best to work up toward elbow height maybe above, easier to just push and muscles will work to their best advantage. I have this aquarium I have used standing in end with a board on it - not a good idea really. I've never measured it. It doesn't move around up to 10in with a bucket of water in it. Pitch hardness is a toughy. I've tried the Texereau way - small piece in the mouth, let it warm up and see if you can chew it and still had sleeks at times. I'd guess this has something to do with him using pine rather than coal tar pitch and also him having very high skill levels. He does show coating the lap with beeswax - I couldn't find any at the time that happened. Another more recent view is pressing hard with the thumb nail. If an impression forms in under say 1/2 min or some level approaching that forget it as it's too soft. Pitch hardness will alter the amount of drag the lap has. Some people pre polish - charge the lap with one of the abrasives rather than rouge. Might correct things more quickly but I have no idea if the lap is any good for anything else afterwards. Too small a lap and it will probably just cause problems more quickly. For the next one I want to make a machine. Main reason is that I want to put it on a shelf in my workshop when it's running - bit difficult to walk round a shelf. No stroke arm as I can do that for the brief time it's needed compared with the time to do the rest. RPM has been tricky to sort out but from looking around I'm settling on about 15rpm, no more that 20. That's based on pro machines - usually intended for smaller work. Adding a stroke arm makes things more tricky even to the point of deciding on a sensible rate that wont produce patterns in the work. The Waite's video's on youtube are a good source of info on how to use a fixed post machine. Could add a manual stroke arm anyway easily. Maybe Damian might realise that any comments I make are largely down to concern about the experience he is having and nothing else. As I see it there is a lot of junk about on the web concerning making precision mirrors and people can easily be miss lead and I feel that is where Texereau comes in. Little has changed really other than the materials used. It's a pity he didn't do another on bigger faster mirrors because that does need some changes. He does give sufficient info to work out how much glass needs to be removed to figure if I remember correctly - if that gets up to 0.001in it will be a lot of work. I don't think Damian is any where near that though and probably in real terms due to the size of a lap trying to figure a sphere. Something up to 15,16in should be a lot better but will still take a while to polish out to the edge and too much overhang will probably turn the edge. The idea of the sphere forming is all down to random motion as a sphere is the only shape that can cope with that and remain in contact. Anyway Damian probably has muscles like Popeye now. Don't give up. You've learnt a lot all ready. I just feel some one should have posted the above some time ago. Some will have been there. I have been lucky. John -
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